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BackgroundReporting retention data is critical to determining the soundness of a study's conclusions (internal validity) and broader generalizability (external validity). Although selective attrition can lead to overestimates of effects, biased conclusions, or overly expansive generalizations, retention rates are not reported in many longitudinal studies.MethodsWe examined multiple child- and family-level factors potentially associated with retention in a longitudinal study of younger siblings of children with autism spectrum disorder (ASD; n = 304) or typical development (n = 163). The sample was followed from the first year of life to 36 months of age, for up to 7 visits.ResultsOf the 467 infant siblings who were consented and participated in at least one research visit, 397 (85.0%) were retained to study completion at 36 months. Retention rates did not differ by familial risk group (ASD-risk vs. Low-risk), sex, race, ethnicity, age at enrollment, number of children in the family, maternal employment, marital status, or parent concerns about the child at enrollment. A stepwise regression model identified 4 variables that, together, provided the most parsimonious predictive model of study retention: maternal education, maternal age at child's birth, travel distance to the study site, and diagnostic outcome classification at the final study visit.ConclusionsThe retained and not-retained groups did not differ on most demographic and clinical variables, suggesting few threats to internal and external validity. The significantly higher rate of retention of children diagnosed with ASD (95%) than typically developing children (83%) may, however, present biases when studying recurrence risk. We conclude by describing engagement and tracking methods that can be used to maximize retention in longitudinal studies of children at risk of ASD.

Objective: We evaluated trajectories of attention-deficit/hyperactivity (ADHD)-relevant behaviors in a sample of infants at high and low familial risk for ADHD who were prospectively evaluated at 12, 18, and 24 months of age.Method: Participants included 43 infants at risk for ADHD based on family history (i.e., diagnosed first-degree relative) and 40 low-risk infants (i.e., no family history of ADHD). Instances of inattention, out-of-seat, and grabbing behavior were coded from video; analogous constructs were rated by examiners unaware of familial risk status after completing structured standardized assessments with the infants/toddlers. At the end of each study visit, examiners solicited parents' concerns about their child's behavior. Differences in ADHD-related behaviors and parent concerns were examined between 12 and 24 months of age.Results: Infants with an older sibling or parent diagnosed with ADHD were distinguishable from infants with no family history of ADHD as early as 12 months of age based on directly observed and examiner reports of behavior, particularly with respect to hyperactive-impulsive behavior. Parents of infants at familial risk for ADHD also reported significantly more behavior/temperament concerns as early as 12 months of age compared to parents of infants at low risk for ADHD.Conclusions: These findings highlight the ability to detect genetic liability for ADHD by the end of the first year of life, suggesting that well-designed family risk studies of ADHD are feasible and may be clinically valuable. They also suggest the potential for earlier detection of risk for ADHD than has previously been possible.

BackgroundSigns of autism are present in the first 2 years of life, but the average age of diagnosis lags far behind. Instruments that improve detection of autism risk in infancy are needed. This study developed and tested the psychometric properties of a novel video-based approach to detecting ASD in infancy.MethodsA prospective longitudinal study of children at elevated or lower risk for autism spectrum disorder was conducted. Participants were 76 infants with an older sibling with ASD and 37 infants with no known family history of autism. The Video-referenced Infant Rating System for Autism (VIRSA) is a web-based application that presents pairs of videos of parents and infants playing together and requires forced-choice judgments of which video is most similar to the child being rated. Parents rated participants on the VIRSA at 6, 9, 12, and 18 months of age. We examined split-half and test-retest reliability; convergent and discriminant validity; and sensitivity, specificity, and negative and positive predictive value for concurrent and 36-month ASD diagnoses.ResultsThe VIRSA demonstrated satisfactory reliability and convergent and discriminant validity. VIRSA ratings were significantly lower for children ultimately diagnosed with ASD than children with typical development by 12 months of age. VIRSA scores at 18 months identified all children diagnosed with ASD at that age, as well as 78% of children diagnosed at 36 months.ConclusionsThis study represents an initial step in the development of a novel video-based approach to detection of ASD in infancy. The VIRSA's psychometric properties were promising when used by parents with an older affected child, but still must be tested in community samples with no family history of ASD. If results are replicated, then the VIRSA's low-burden, web-based format has the potential to reduce disparities in communities with limited access to screening.

While previous studies suggested that regressive forms of onset were not common in autism spectrum disorder (ASD), more recent investigations suggest that the rates are quite high and may be under-reported using certain methods. The current study undertook a systematic investigation of how rates of regression differed by measurement method. Infants with (n = 147) and without a family history of ASD (n = 83) were seen prospectively for up to 7 visits in the first three years of life. Reports of symptom onset were collected using four measures that systematically varied the informant (examiner vs. parent), the decision type (categorical [regression absent or present] vs. dimensional [frequency of social behaviors]), and the timing of the assessment (retrospective vs. prospective). Latent class growth models were used to classify individual trajectories to see whether regressive onset patterns were infrequent or widespread within the ASD group. A majority of the sample was classified as having a regressive onset using either examiner (88%) or parent (69%) prospective dimensional ratings. Rates of regression were much lower using retrospective or categorical measures (from 29 to 47%). Agreement among different measurement methods was low. Declining trajectories of development, consistent with a regressive onset pattern, are common in children with ASD and may be more the rule than the exception. The accuracy of widely used methods of measuring onset is questionable and the present findings argue against their widespread use. Autism Res 2018, 11: 788-797. © 2018 International Society for Autism Research, Wiley Periodicals, Inc.Lay summaryThis study examines different ways of measuring the onset of symptoms in autism spectrum disorder (ASD). The present findings suggest that declining developmental skills, consistent with a regressive onset pattern, are common in children with ASD and may be more the rule than the exception. The results question the accuracy of widely used methods of measuring symptom onset and argue against their widespread use.

ObjectiveThis study had 3 goals, which were to examine the following: the frequency of atypical development, consistent with the broader autism phenotype, in high-risk infant siblings of children with autism spectrum disorder (ASD); the age at which atypical development is first evident; and which developmental domains are affected.MethodA prospective longitudinal design was used to compare 294 high-risk infants and 116 low-risk infants. Participants were tested at 6, 12, 18, 24, and 36 months of age. At the final visit, outcome was classified as ASD, Typical Development (TD), or Non-TD (defined as elevated Autism Diagnostic Observation Schedule [ADOS] score, low Mullen Scale scores, or both).ResultsOf the high-risk group, 28% were classified as Non-TD at 36 months of age. Growth curve models demonstrated that the Non-TD group could not be distinguished from the other groups at 6 months of age, but differed significantly from the Low-Risk TD group by 12 months on multiple measures. The Non-TD group demonstrated atypical development in cognitive, motor, language, and social domains, with differences particularly prominent in the social-communication domain.ConclusionsThese results demonstrate that features of atypical development, consistent with the broader autism phenotype, are detectable by the first birthday and affect development in multiple domains. This highlights the necessity for close developmental surveillance of infant siblings of children with ASD, along with implementation of appropriate interventions as needed.